Last week, the Guttmacher Institute released an analysis of the recent decline in the incidence of abortion. Overall, the abortion rate declined by an impressive 13 percent between 2008 and 2011 and reached its lowest level since 1973. This Guttmacher analysis joins a chorus of pundits — including Andrew Sullivan — who were quick to credit contraception for this decline in the abortion rate. And like most Guttmacher studies, this analysis is quick to downplay pro-life laws and other pro-life efforts.

The author presents some data which suggests that contraception use did increase during this time span. There is less than meets the eye here, however. The author finds that fewer women under 30 at risk for an unintended pregnancy were forgoing contraception. Yet the decline was slight — only three percentage points. The study also cites increases in the percentage of women using Long Acting Reversible Contraceptives (LARCs), but its data on LARC use ends in 2009 and hence, only covers a fraction of the years the abortion rate was falling. More importantly, less than 10 percent of contraceptive users rely on LARCs and LARCs tend to have a high discontinuance rate.

The author makes a fair point that the abortion decline was fairly consistent throughout the country and was not concentrated in states that were active in passing pro-life laws. He correctly points out the sharp increase in state-level pro-life laws took place after the abortion decline already happened. However, the study presents a false dichotomy between either crediting legislation or crediting contraceptives for the falling abortion numbers. Indeed, it neglects other factors such as public opinion. In 2009, for the very first time, Gallup reported that a majority of Americans described themselves as “pro-life.” The link between abortion attitudes and abortion incidence is not well documented. That said, the shift in public opinion is still worth considering.

A longer term analysis of abortion trends reveals insights which weaken Guttmacher’s case. Last month, the Charlotte Lozier Institute released a study by Susan Wills analyzing the U.S. abortion decline from 1990 to 2010. The key finding is that the abortion decline has not been uniform among age groups. The declines have been the greatest in both absolute and percentage terms among teens and women in their early 20s. This is important for two reasons. First, LARCs, which are touted by Guttmacher, tend to be unpopular with this subset of women. Second, there is a growing body of data showing declines in teen sexual activity since the early 1990s. As such, contraceptive use may be playing less of a role in the long-term abortion decline than the Guttmacher analysis would indicate.

Additional analysis further weakens Guttmacher’s argument. According to its own statistics, the number of abortions has fallen by roughly 34 percent since 1990 and the abortion rate has fallen by 38 percent since that time. It is true that contraception use has increased since the early 1990s, but it’s also true that contraception use has been rising steadily since the early 1960s, and obviously predates the abortion decline by a significant number of years. More importantly, even though contraceptive use has gone up, the fertility rate and unintended pregnancy rate have both actually increased slightly since the mid-1990s. All in all, pro-life efforts to change the hearts and minds of women facing crisis pregnancies might be more effective than commonly realized.

— Michael J. New is an assistant professor at the University of Michigan–Dearborn and an adjunct scholar at the Charlotte Lozier Institute. Follow him on twitter @Michael_J_New